Electron discharge device of the magnetron type



Oct. 26, 1948 H. G. ANDERSON 2,452,032

ELECTRON DISCHARGE DEVICE OF THE MAGNETRON TYPE Filed June 10, 1944 Patented Oct. 26, 1948 UNITED '5" EMT QFFICE ELECTRON DISCHARGE DEVICE OF THE RdAGNETR-ON TYPE Application June 10, 1944, Serial No. 539,722

'7 (llaims. i

This invention relates to electron discharge devices, and more particularly to those using an output coupling comprising a loop or other energy absorbent part located within the anode structure.

In electron discharge devices having a plurality of resonant cavities, it is desired that the period of oscillations of all of the resonant cavities shall be the same. In electron discharge devices, however, using an output coupling comprising an energy absorbent part within the anode structure, such as an output coupling of the loop type, for example, in which the loop is located within one of the resonant cavities of the device, the presence of the loop or other energy absorbent part within said cavity tends to infiuence the field distribution of the resonator and to create disturbing efiects, more particularly capacity 'eifects between the loop and the anode plates, and tends to give rise to objectionable variations between the period of the oscillations of the cavity in which the loop is located and the period of the oscillations of the remaining resonant cavities.

One of the objects of the present invention is I to provide means for counteracting the aforesaid objectionable capacity effects.

Furthermore, output coupling loops for said electron discharge devices have heretofore of necessity been relatively small, owing to the fact that the larger the loop, the greater will be the objectionable capacity effects between the anode plates and the loop. This limitation to the use of relatively small loops is a distinct disadvantage as energy heretofore wasted would be absorbed by a loop of greater area, thus increasing the output of the device.

Another object of the present invention is therefore to provide means permitting the use of a loop or equivalent part having a greater energy absorbent area.

I A further object of the present invention is to attain the last-named object Without the production of objectionable capacity effects between the anode plates and the loop or equivalent part.

The aforesaid objects, and such other aims and objects of the invention as may hereinafter appear, will be readily understood from the following description, taken in connection with the accompanying drawing of one embodiment of the invention herein presented for illustrative purposes.

In the drawing:

Fig. 1 is a vertical section of an electron discharge device incorporating one illustrative embodiment of the invention;

Fig. 2 is a cross-section on line 22 of Fig. 1'; allfl Fig. 3 is a perspective View, partly in section, showing the output coupling loop and associated parts, and their relative positions.

Referring to the drawing, the electron discharge device therein illustrated comprises an envelope 2 closed at both ends by caps 4 and ii hermetically soldered in place. Said envelope and said caps are made of conductive material, copper, for example, and the envelope is formed with a central, annular projection 8 along the inner surface of which are soldered a plurality of radial plates Hi, which may be stamped out of a sheet of highly conductive copper. The inper ends of said plates I9 constitute anode faces which cooperate with a cathode l2 supported substantially centrally of said anode faces and preferably of the indirectly-heated, oxide-coated, thermionic type comprising an outer conducting sleeve ii coated with electron emissive oxides and provided with an internal heater, not shown, of which the end conductors H5 and I8 project from the opposite ends of said cathode structure i2. One of said conductors, the conductor I6 for example, may be electrically connected to said cathode sleeve i l, the other conductor being insulated from said sleeve. shieids 2E] and 22 may be supported adjacent the two ends of said cathode to prevent electron beams from being projected against said caps 4 and 8. The cathode i2 is conveniently supported by a lead-in conductor 2% welded to the free end of conductor iii which as above stated is electrically connected to said cathode and to one end of the cathode heater. Said lead-in conductor 24 is sealed through a conventional glass seal, not shown, mounted at the outer end of a conducting pipe 25 hermetically fastened through the wall of said envelope 2 near its lower end. A second lead-in conductor 25 similar to saidconductor'M is Welded to the conductor l8 and sealed through a second glass seal mounted at the outer end of a second conducting pipe, also hermetically sealed through the wall of said envelope 2 at its upper end. Said second lead-in conductor and said second conducting pipe and its seal are similar in all respects to the conductor pipe 24, and its seal, and are therefore not shown in order not to complicate the drawing.

When an electron discharge device of the type described. is placed between suitable magnetic poles 27 and 28 so as to excite a longitudinal Light conducting magnetic field, and said device is energized, oscillations will be set up which may be led out of the device by a suitable output coupling provided with a part, such as a loop 30, for example, extending into the resonant cavity between two adjacent anode plates or arms i0. One end 32 of said coupling loop 30 is connected to the inner end of a conducting pipe 34 hermetically sealed through the wall of said envelope substantially midway between the ends thereof. At its other end said coupling loop 30 is connected to a conductor 36 which extends through said pipe 34 and is sealed through a glass seal 38 mounted at the outer end of said pipe. For the purpose of simplicity, said pipe is shown in Fig. 2 as broken away at its central portion. An additional conducting pipe, not shown, may be electrically connected to said pipe 34 and form with the conductor 3 6 a concentric line through which high frequency oscillations generated by the device may be conducted to a suitable utilization circuit.

Each pair of anode plates or arms Ill forms with the portion of the central projection 8 between them an oscillating cavity. A capacitance exists between the cathode l2 and the end faces of the anode arms or plates and also between the side walls of each oscillating cavity. The conductive path around each cavity afforded by the side walls thereof constitutes an inductance. The anode, therefore, is so designed and spaced relatively to the cathode that the inductances and capacitances described constitute tuned circuits. It is desired that these circuits shall be resonant at a definite, predetermined frequency at which the device is to operate. The device is intended to operate so that each oscillating cavity shall be tuned to the frequency at which each of the other oscillating cavities oscillates.

Referring to the illustrative embodiment of the invention shown in the drawing, the means for realizing the objects of the present invention herein illustratively comprise opposed recesses Ml and 42 provided in the inner surfaces of the two electron-receiving arms l9 respectively forming the lateral walls of the resonant cavity within which the loop or other energy absorbent part is located. One leg 44 of said loop is opposite one of said recesses, the recess for example, and the other leg 46 of said loop is opposite the other recess 42. Each leg will preferably be substantially parallel to the anode arm adjacent thereto. A convenient way to form said recesses 48 and 42 is to bore radially inward with a drill of the required diameter, through the wall of the envelope'2, between two selected adjacent anode arms [10, and continue the bore into the inner surfaces of said two adjacent anode arms a distance sufiicient to form the recesses 40 and 42 substantially as illustrated.

It will be noted that in accordance with the present invention the output coupling loop, instead of being located between plane surfaces of the anode plates at either side thereof, is located between recesses provided in said surfaces, so that the anode plate surfaces between which said loop is located are now further removed from the two legs of said loop than formerly. It is this circumstance which, according to my present understanding of the operation of my invention, is responsible for the elimination of the objectionable capacity efiects previously referred to and of the consequent objectionable variations in the period of oscillations, and which enables a loop of greater energy absorbent area to be used, thus to increase the ratio of energy absorbed by the loop to that generated by the device, whereby the output of the device may be materially increased.

The present invention represents an important and useful advance in the art. It has practically eliminated the objectionable influences attributable to the presence of the coupling loop in the device or so reduced them that their effect is negligible. It has made available a greater quantity of the energy generated by the device than was heretofore the case, thus materially increasing the output of the device. Furthermore it attains these useful results in a simple and efiicient manner without the addition to the tube of any structure.

I am aware that the present invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present description to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the aforesaid description to indicate the scope of the invention.

What is claimed is:

1. An electron discharge device comprising an envelope containing a cathode and an anode, said anode comprising a pair of electron-receiving portions adjacent said cathode, and a cavity resonator interconnecting said pair of electron-receiving portions, the opposed inner surfaces of said cavity resonator being each provided with a recess the longitudinal axis of which lies in a plane perpendicular to the longitudinal axis of. said cavity resonator, and an output coupling loop located within said cavity resonator and between said recesses.

2. An electron discharge device comprising an envelope containing a cathode and an anode, said anode comprising a pair of electron-receiving portions adjacent said cathode, and a cavity resonator interconnecting said pair of electron-receiving portions, the opposed inner surfaces of said cavity resonator being each provided with a recess, and an output coupling loop located within said cavity resonator and between said recesses, each of the legs of said loop being substantially parallel to the inner surface of said cavity resonator adjacent thereto.

3. An electron discharge device comprisingv an envelope containing a cathode and an anode, said anode comprising a pair of electron-receiving portions adjacent said cathode, and a cavity resonator interconnecting said pair of electron-receiving portions, the opposed inner surface of said cavity resonator being each provided with a recess, and an output coupling loop located within said cavity resonator and between said recesses, said loop being located in a plane substantially perpendicular to the opposed inner surfaces of said cavity resonator.

4. An electron discharge device comprising'a, cavity resonator, opposed walls of said cavity resonator being provided with recesses the longi tudinal axes of which lie in a plane perpendicular to the longitudinal axis of said cavity resonator, and an output coupling comprising an energy absorbent loop within said cavity resonator between said recesses.

5. An electron discharge device comprising a cavity resonator, opposed walls of said cavity resonator being provided with substantially par-" allel recesses, and an output coupling comprising an energy absorbent loop located between said recesses in a plane substantially parallel to the longitudinal axes of said recesses.

6. An electron discharge device comprising a cavity resonator, opposed Walls of said cavity resonator being provided with substantially parallel recesses, and an output coupling comprising an energy absorbent loop located between said recesses, said loop comprising two legs located in a plane substantially parallel to the longitudinal axes of said recesses, each of said legs being substantially parallel to the wall of said cavity resonator adjacent thereto.

7. An electron discharge device comprising a cavity resonator, opposed walls of said cavity resonator being provided with substantially parallel semi-cylindrical recesses, and an output coupling comprising an energy absorbent loop located between said recesses, said loop comprising two legs located in a plane substantially parallel to the longitudinal axes of said recesses, each of said legs being substantially parallel to the wall of said cavity resonator adjacent thereto.

HOMER G. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

